Military fighter and attack aircraft of the fourth generation are designed as basically statically unstable aircraft, which are stabilized with an electrical flight control system continuously adjusting a number of control surfaces. This design is chosen in order to achieve the highest possible performance throughout the total flight envelope. The electrical flight control system uses sensor information regarding aircraft flight parameters such as pitch, roll, and yaw. The system also receives and utilizes information regarding wind and gusts. The primary purpose of using the information is to minimize the influence from external disturbances, which may deteriorate performance and other control performances, in order to gain better aircraft and weapon system performance. Information can come from internal gyro signals and from total and static pressure (pitot tubes) and angle-of-attack and sideslip (alpha and beta vanes).
However, some difficulties may arise when such an aircraft unintentionally passes through wake vortices from another aircraft. The continuously adjusting electric control system receives sensor signals from the wake vortex passage, that give rise to unintentional control surface movement and an unintentional aircraft response. This can lead to angle of attack overshoots above the angle of attack limits.
An object of the present invention is therefore to provide a solution that reduces the risk for diminished control of a fourth generation aircraft when passing through wake vortices.